<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <STYLE>
        h1 {
            color: red;
            font-size: 10px;
        }

    </STYLE>

    <script>

        var num = prompt("请输入一个数")
        if (num % 2 === 0) {
            alert("偶数")
        }

    </script>
</head>
<body>
<h1>dashkhkd</h1>
<a href="https://www.baidu.com">百度一下</a>

</body>
</html>